The invention is based on a state of the art known from NL-A 8001933. A boat reversing gear is illustrated and described in this state of the art, wherein two gears are supported on a driven shaft and can be coupled by means of a gearshift sleeve and friction clutches, also arranged on the drive shaft, selectively with the shaft. Radially directed bolts are arranged in the gearshift sleeve, one end projecting inwardly out of the gearshift sleeve and into a groove, extending inclined with respect to the plane of rotation, in the driven shaft. The gearshift sleeve is held in a neutral position by means of spring-loaded notches. If an axial force is applied by a lever from outside onto the gearshift sleeve, then the notches are released against their force and the gearshift sleeve is both rotated relative to the shaft and also moved axially through the bolts resting on the groove walls, whereby the friction clutch is engaged and the associated gear is thereby coupled with the shaft.
Even if the friction members of the clutch are supported against a spring, engaging still occurs almost instantaneously. The thereby occurring, so-called engaging impact, can be noticed by a jerking sensation which depending ont he intedsity - is uncomfortable at times in the boat and can also be noticed acoustically.
Furthermore, it is considered to be disadvantageous in the known coupling construction that the force needed for disengaging the clutch is rather great, which is particularly bad during maneuvering or, if in a case of danger a quick reversing of gears is needed.
A guide sleeve which is fixed against rotation, however, is axially movabely mounted on the shaft, is known from German OS No. 28 28 722 in connection with a different type of construction of shiftable friction clutches.
Therefore, the basic purpose of the invention is to provide a friction clutch of the mentioned type so that the mentioned disadvantages are avoided.